Revert "powerpc: Rework dma-noncoherent to use generic vmalloc layer"

This reverts commit 33f00dcedb0e22cdb156a23632814fc580fcfcf8.

    While it was a good idea to try to use the mm/vmalloc.c allocator instead
    of our own (in fact, ours is itself a dup on an old variant of the vmalloc
    one), unfortunately, the approach is terminally busted since
    dma_alloc_coherent() can be called at interrupt time or in atomic contexts
    and there's little chances we'll make the code in mm/vmalloc.c cope with\       that :-(

    Until we can get the generic code to forbid that idiocy and fix all
    drivers abusing it, we pretty much have no choice but revert to
    our custom virtual space allocator.

    There's also a problem with SMP safety since freeing such mapping
    would require an IPI which cannot be done at interrupt time.

    However, right now, I don't think we support any platform that is
    both SMP and has non-coherent DMA (don't laugh, I know such things
    do exist !) so we can sort that out later.

    Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a0d1146a0578..3bb43adce44d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -868,6 +868,31 @@ config TASK_SIZE
         default "0x80000000" if PPC_PREP || PPC_8xx
         default "0xc0000000"
 
+config CONSISTENT_START_BOOL
+        bool "Set custom consistent memory pool address"
+        depends on ADVANCED_OPTIONS && NOT_COHERENT_CACHE
+        help
+          This option allows you to set the base virtual address
+          of the consistent memory pool.  This pool of virtual
+          memory is used to make consistent memory allocations.
+
+config CONSISTENT_START
+        hex "Base virtual address of consistent memory pool" if CONSISTENT_START_BOOL
+        default "0xfd000000" if (NOT_COHERENT_CACHE && 8xx)
+        default "0xff100000" if NOT_COHERENT_CACHE
+
+config CONSISTENT_SIZE_BOOL
+        bool "Set custom consistent memory pool size"
+        depends on ADVANCED_OPTIONS && NOT_COHERENT_CACHE
+        help
+          This option allows you to set the size of the
+          consistent memory pool.  This pool of virtual memory
+          is used to make consistent memory allocations.
+
+config CONSISTENT_SIZE
+        hex "Size of consistent memory pool" if CONSISTENT_SIZE_BOOL
+        default "0x00200000" if NOT_COHERENT_CACHE
+
 config PIN_TLB
         bool "Pinned Kernel TLBs (860 ONLY)"
         depends on ADVANCED_OPTIONS && 8xx